Circuit commutating device



Aug 8, 1939. J. L, DEFANDORF x-:r AL 2,169,039

CIRCUIT COMMUTATING DEVICE Filed Oct. 23, 1956 2 Sheets-Sheet l g-ITA112 8, 1939. J. 1 DEFANDORF Er AL 2,169,039

CIRCUIT COMMUTAT ING DEVICE Filed Oct. 25, 1956 2 ShQetS-Shee 2 *fumPatented Aug. 8, 1939 UNITED STATES PATENT OFFICE cmcm'r coMMUTATINGDevice tion of Delaware Application October 23, 1936, Serial No. 107,154

11 Claims.

This invention relates to circuit commutating devices and is especiallyapplicable to float operated devices employing mercury switches.

Such iioat operated devices are commonly required to control a pluralityof circuits, a separate mercury switch being employed for each circuit.Muti-circuit devices of such character are commonly employed forcontrolling motor driven pumps for supplying or withdrawing fluid, andin practice the switch control required for different applicationsvaries widely. It may be desired in one instance to have a certainswitch close at a given level oi' fluid and open at certain differentfluid level, whereas in another instance it may be desired to have thesame switch operate at other selected levels with or without a change indifferential between the selected levels. Also it may be desired to havethe several switches function in a given relation in some instances andin a different relation in other instances. 'Ihus a very flexibleadjustment is required to avoid need of a multiplicity of differentlydesigned devices.

The present invention has among its objects to provide a highlysatisfactory fioat operated device of the character set forth having thedesired flexibility of adjustment.

Another object is to provide a very flexible multi-circuit deviceadvantageous for various other uses, especially where the operatingforce available is small and where the quick action characteristic ofmercury switches is desired.

Another object is to provide for such flexibility of adjustment in amulti-circuit device having oscillating cam operating means and t0provide for switch closing and opening operations, each within a smallpart of the range of movement of the oscillating cam operating means.

Another object is to provide for reliability of functioning of theswitches whatever the adjustment may be and to obtain such reliabilitywithout requiring a troublesome degree of exactness in constructing thedevice.

Other objects and advantages of the invention will hereinafter appear.

One embodiment of the invention is illustrated in the accompanyingdrawings, and the same will now be described, it being understood thatthe invention is susceptible of various modifications without departingfrom the scope of the appended claims.

In the drawings,

Figure l is a perspective view of a float operated device with its coverremoved;

Fig. 2 is a detailed view, partly in section, show- (Cl. 2ML-18) ing oneof the mercury switch units of Fig. l;

Fig, 3 is a sectional view taken on line 3-3 of Fig. 2;

Fig. 4 is a sectional view taken on line 4 4 of Fig. 2; 5

Fig. 5 is an enlarged detail view of the trunnion bearings shown in Fig.3;

Fig. 6 shows the cam parts of one switch, and Fig. 7 shows, partly insection and partly in elevation, the cam assembly for the several l0switches of Fig. l.

Referring to Fig. 1, the same shows four mercury switch units I, 2, 3and 4 carried by a supporting bar 5 which in turn is supported bybrackets 6 and 1 mounted within a box 8 having a cover, not shown. Theswitch units have multiplate operating cams 9, I0, II and I2,respectively, carried by a shaft I3 mounted in brackets 6 and 1 andhaving fixed thereto at one end a gear I4 meshing with a gear I5 carriedby a shaft I6 mounted in bracket 1, and having xed thereto a sheavewheel II to which is attached a float I8 by a rope or cable I9. Theopposite end of the cam shaft I3 has fixed thereto a sheave wheel 20 towhich is connected a counterweight 2| by a rope or cable 22. 'I'husprovision is made for oscillating the cam shaft as the oat I8 is raisedand lowered through variation in fluid level, the shaft being oscillatedthrough a range of about 300 degrees.

As will be understood, such a device may be required for control of oneor a plurality of motor driven pumps for either supplying or exhaustingfluid, the motor 0r motors to be controlled in any of various differentways. Also as will be understood, according to the circuit commutationsdesired the number of switch units employed may be either increased ordecreased, the switches commonly being adjusted for some difference inperformance, although of course two or more 40 switches might if desiredbe adjusted to function to make and/or break circuit at the same time,and the cams being provided to aord the desired performance of theseveral switches.

The several switch units are of like construc- 45 tion being constructedas illustrated in Figs. 2 to 5. Referring to Fig. 2, which may beassumed to show unit I, said unit' comprises a conventional type ofmercury switch 25 shown only in outline, it being understood that saidswitch comprises 50 metal electrodes and a body of mercury to make andbreak the circuit including said electrodes, and preferably providing amercury to mercury break. Also as will be understood, the switch 25, asis customary, makes and breaks circuit upon tilting thereof. 'I'heswitch 25 as shown in Figs. 2. 3 and 5 is surrounded by a clamped onband 24 which as best shown in Figs. 3 and 5 has diametrically opposedopenings to receive the heads of trunnions 21 and 23 respectively.carried by supporting plates 29 and 30,. each attached to supportingbase 5 through the medium of a pin 3|. The pins 3| are carried by blocks32 on base 5 and project from the blocks to enter openings in theplates, the latter being thereby loosely supported and being connectedat their upper ends by a tension spring 33. Each of the trunnions 21 and23 preferably has a drive fit with its respective supporting plate, andsaid supporting plates under the action of spring 33 press the heads ofthe trunnions against the casing of the switch, which may be Bakelite orother preferred material, to frictionally hold the switch againstaccidental oscillation about itsaxis afforded by the trunnions. However,the switch will respond to4 a slight pressure to turn on itsaforementioned axis for making and breaking circuit, and it may beassumed that the switch is rotated anticlockwise to make circuit, andclockwise to break circuit, although the reverse action might beprovided for if desired. For tilting or oscillating the switch there isprovided a cradle comprising parallel plates 34 and 35 and a connectingend piece 36, said side plates receiving therebetween the switchsupporting plates 29 and 3B, and being respectively mounted on thetrunnions 21 and 23 whereby said cradle is pivotally supported by theswitch supporting plates, the latter having square ends adjacent theupper surface of the base I which insure against an appreciableoscillation of said switch supporting plates on pins 3|. The cradle hasat its outer end a roller 31 carried by a shaft 38 having bearings inthe side plates 34 and 35 of the cradle. Also the cradle carriestransversely extending pins 33 and 4l passing through and supported byits side plates, these pins, as best shown in Fig. 2, affording a lostmotion connection between the cradle and the switch 25.

As will be understood, the roller 31 is provided to rest upon one of theaforementioned operating cams, being biased into engagement therewith byits own weight and the weight of the cradle and when the cradle islifted it acts through the medium of the pin 40 to move the switch 25counterclockwise, whereas when it drops it acts through the medium ofthe pin 35 to move the switch 25 clockwise. However, it will be observedthat when the cradle has been lifted t0 rotate the switch 25counterclockwise, the cradle must be lowered an appreciable distance tobring the pin 39 into engagement with the casing of switch 25 and thatin the meantime switch 25 is frictionally held by trunnions 21 and 23 inits extreme position. Similarly the switch 2l is frictionally held inits opposite extreme position during takeup of the play between theswitch and the pin 40 of the cradle. Thus after each operation of theswitch the cradle may be returned to an intermediate position for apurpose hereinafter set forth, whereas the switch will be frictionallyretained in an extreme position to interrupt or preserve continuity ofcircuit, as the case may be.`

The cam 9 which is typical of all of the aforementioned cams, comprises,as best shown in Fig. 6, a circular plate 42 against opposite sides ofwhich are to be clamped cam members 43 and 44. The cam member 43 is ofcircular form with a fiat peripheral portion 45, said cam being of oneof the switch cradles rides on the edges of these cam members and whenit rides onto one of the converging edges 41 of cam member 44 it liftsits cradle to move its switch counterclockwise into one extremeposition. 0n the other hand, when the roller 31 passes onto the at edgeof cam member 43 it permits the cradle to drop to move the switchclockwise into its other entreme position. Riding of the roller on thecurved edge of cam 43 causes the cradle to assume the aforementionedintermediate position. 'I'hus provision is made for opening and closing,the switch in given angular positions of the driving shaft of plate 42according to the relation in which cam members 43 and 44 are clampedagainst plate 42, and obviously the anthe switch from one extremeposition to the other lmay be varied by turning one cam member relativetothe other for varying the spacing of the high and low points of thecam. Moreover it will be observed that when the cam members arerelatively adjusted for movement of the switch from one extreme positionto another by a given angular throw of the driving shaft' of plate 42,the cam members may be shifted together relative to the plate 42 tochange the angular positions to which the shaft must be moved to openand close the switch. Accordingly with the angular position of the shaftgoverned by the position of the float the switch may be readily adjustedto open and close at predetermined levels to be selected as desired withany desired dinerential regardless of the adjustment of any otherswitch. Also it will be observed that close adjustments of each switchare made possible since the switch necessarily attains one extreme,position during travel of the cam over one of the relatively shortconverging edges 41 of cam member 44 and necessarily attains its otherextreme position as the roller passes onto the relatively short dat edge45 of cam member 43.

Referring to Fig. 7, the shaft |3 carrying the cams h as an intermediateportion 48 which is rectangular in cross section to closely fitrectanglar central openings in the several plates 42. 'I'he plates 42are thereby keyed to the shaft, whereas their respective cam members areprovided wlth circular central openings having clearance 1with theshaft. Between adjacent cam members are arranged tubular spacers 50which have rectangular openings closely fitted by the 1 shaft and whichare provided with annular shoulders 5| forming bearings for the cammembers spaced thereby. One extreme cam member is supported on anannular shoulder 52 of tubular element 53 which spaces said cam memberfrom a nut 54 screwed onto the shaft at its left hand end, said elementenclosing a coiled spring 55 surrounding the shaft and bearing againstthe nut 54 to bias the assembly of plates, cam members and spacerslongitudinally of the shaft toward the right hand end of the shaft.. Theright hand end of the shaft has threaded thereon a nut 55 bearingagainst a washer 51 which forms an abutment for the outside cam member44 and which also has an annular shoulder similar to those of thespacers for supporting said cam member. With the nut 56 set up tight onthe shaft the parts mounted on the square section oi' the shaft aredriven against nut v54 for tight clamping of the cam members againsttheir respective plates 42, and when it is desired. to adjust one ormore cam members the nut' 56 is loosened. The spring 55 then cornes intoplay to maintain friction between each of the cam members and itsrespective plate 42 whereby adjustment of any cam member may be effectedby overcoming this friction while the remaining cam members are held bysuch friction against accidental displacement.

While it is preferred to provide lost motion connectionsI between theswitches and their cradles and to provide friction means for theswitches as set forth, it should be noted that the cam operating meansdisclosed enables both aforementioned provisions to be dispensed withwhere each mercury switch can be relied upon to maintain circuit andalternatively to prevent establishment of circuit while occupying agiven position intermediate its extreme positions. As will beunderstood, many mercury switches after being tilted either to break ormake circuit may be returned to a given position without further circuitcommunicating action of the mercury, but in many instances such returnmovement leaves the mercury in a very unstable state. On the other hand,certain switches are of such design that when returned to anintermediate position they will reliably preserve the last circuitcommutation whether it be interruption or completion of circuit. Thuswhere the device is equipped with the latter type of switch it ispossible, assuming positive connections between each switch and itscradle, to use the cam surfaces 41 and 45 to effect movement' of theswitch to its extreme positions respectively and the curved edge of cammember 43 to effect return of the switch to said intermediate positionimmediately following movement to either extreme position and tomaintain it in such position without change of the last establishedcircuit condition pending a directed change in circuit condition.'Moreover since the switch occupies an intermediate position a veryslight further tilting thereof will render it effective for furthercircuit commutation.

In either case provision is made for effecting tilting of the switchfrom its position of rest to the desired circuit chan-ging position by arelatively small angular motion of the cam shaft and for renderingavailable for range variation the remaining angular motion of the camshaft. As will be understood, either cam member might be made doubleacting within the angular throw provided therefor, if desired. Also aswill be understood, the lost motion and friction provisions hereinbeforeset forth have the advantage of enabling successful use of mercuryswitches responsive upon slight angular movement thereof and -withoutnecessitating the troublesome exactness of design and manufacture of theoperating mechanism which would be required should a small throw switchbe employed without such lost motion and friction provisions.

Obviously complementary cam members 43 and 44 may be adjusted into arelation whereby their respective switch roller will pass directly fromthe edge portion 45 of member 43 to an edge portion 41 of member 44, orvice versa, to effect uninterrupted and quick movement of the switchfrom one extreme position to its other extreme position. Also it will beobvious that if after a switch roller has ridden up one edge 41 of a cammember 44 and down its other edge 41 onto the curved edge of cam member43, the cam member 44 may be moved to again lift and drop the rollerwithout effecting circuit change by the switch pending dropping of therolleronto the flat edge portion of cam member 43 and with the lostmotion connection and frictioning means aforedescribed the position ofthe switch would remain unchanged during such oscillations of member 44.

What we claim as new and desire to secure by Letters Patent is:

1. In a circuit device, the combination with a mercury switch supportedfor oscillation, of a rotary cam having high and low camming surfacesand an intermediate active surface coextensive with the space betweensaid high and low surfaces and concentric with the axis of rotation ofsaid cam, and operative connections between said mercury switch and saidcam comprising a cam follower to engage said three surfaces, saidmercury switch upon movement of said follower onto and over saidintermediate active surface maintaining the circuit commutation lasteffected thereby.

2. In a circuit device, the combination with a mercury switch supportedfor oscillation, of a rotary cam having relatively adjustable membersproviding high and low camming surfaces to be adjusted relatively and anintermediate active surface which is coextensive with the space betweenthe high and low camming surfaces for different adjustments of thelatter and which is concentric with the axis of rotation of said cam,and operative connections between said mercury switch and said camcomprising a cam follower to engage said three surfaces, said mercuryswitch upon movement of said follower onto and over said intermediateactive surface maintaining the circuit commutation last effectedthereby.

3. An adjustable switch operating cam to be mounted for rotationcomprising relatively adjustable members adjustable about the axis ofsaid cam and providing high and low camming surfaces to be adjustedrelatively and an intermediate active surface which is coextensive withthe space between the high and low camming surfaces for differentadjustments of the latter and which is concentric with the axis ofrotation of said members.

4. In a multi-circuit device, the combination with a plurality ofswitches each provided with an oscillatable actuating element having alost motion connection therewith and biased in one direction and each ofsaid switches having means to restrain the same in its extreme positionssubject to release by movement of its actuating element, of a pluralityof cams supported for oscillation together to cooperate with saidactuating elements` of said switches for effecting movement of saidswitches each to opposite extreme positions selectively, said cams eachhaving in a spaced relation relatively short and steep camming surfacesand a surface which is coextensive with the space between said cammingsurfaces and which is concentric to the axis of said cams.

5. In a multi-circuit device, the combination with a plurality ofmercury switches supported for oscillation individually and having meansresisting movement thereof away from either of its extreme positions, ofa plurality of members supported for oscillation individually and havinglost motion connections with said switches respectively, each of saidmembers being biased in one direction and being operable to release itsrespective switch from either extreme position, and a plurality of camssupported for oscillation together to cooperate with said members foreffecting movement of said switches each to opposite extreme positionsselectively, said cams each having in a. spaced relation relativelyshort and steep camming surfaces and also having a surface which iscoextensive with the space between said camming surfaces and which isconcentric to the axis of said cams.

6. In a multi-circuit device, the combination with a plurality ofmercury switches supported for oscillation individually and having meansfrictionally to retain the same in extreme positions, of a plurality ofmembers supported for oscillation individually and having lost motionconnections with said switches respectively, each of said members beingbiased in one direction, of an oscillatable cam member having aplurality of cams to cooperate with said members respectively foreffecting movement of said switches each to opposite extreme positionsselectively, certain of said cams each having relatively adjustablemembers providing high and low camming surfaces to be adjustedrelatively and an intermediate surface which is concentric to the axisof oscillation of said cam member and which is coextensive with thespace between the high and low cam surfaces for diierent adjustments ofthe latter.

7. In a circuit commutating device, the combination with a switchprovided with an actuating element to be reciprocated, said switch beingmovable to open and closed positions selectively by movements of saidelement to extreme positions and saidelement being returnable to a givenintermediate position after opening or closing of said switch withouteffecting further circuit change by the latter, of a cam having asurface which is engaged by said element under bias and which eiectssaid intermediate positioning of said element throughout a range ofmovement of said cam, and said cam having relatively adjustable high andlow camming surfaces pitched abruptly from the first mentioned surfacefor effecting movement of said element into its extreme positionsselectively.

8. In a circuit commutating device, the combination with a switchprovided with an actuating element having a lost motion connectiontherewith, said switch being movable to open and closed positionsselectively by reverse movements of said element to extreme positionsand said-element being returnable to a given intermediate position afteropening or closing of said switch without effecting return movement ofsaid switch, of a cam having a surface which is engaged by said elementunder bias and which effects said intermediate positioning of saidelement throughout a range of movement of said cam and said cam havingspaced and relatively adjustable high and low camming surfaces pitchedabruptly from the first mentioned surface for effecting movement oi'said element into its extreme positions selectively.

9. In a circuit commutating device, the combination with a switchprovided with an oscillatable actuating element, said switch beingmovable to open and closed positions selectively by reverse movements ofsaid element to extreme positions, and said element being returnable toa given intermediate position after opening or closing said switchwithout effecting further circuit change b y the latter, of a cam havinga surface which is engaged by said element under bias l and whicheiiects said intermediate positioning of said element throughout a rangeof movement of said cam, and said cam comprising relatively adjustableparts respectively provided with high and low camming surfaces which arerelatively short and steep and which are engageable with said element toeffect movement of the latter from said intermediate position to itsextreme positions selectively.

10. In a circuit commutating device, the combination with a switchprovided with an oscillatable actuating element, said switch beingmovable to open and closed positions selectively by reverse movementsinto extreme positions and said element being returnable to a givenintermediate position aiter opening or closing said lswitch withouteffecting further circuit change by said switch, of an oscillating camhaving a surface which is engaged by said element under bias and whichis concentric to the axis of oscillation of said cam, and also havingspaced and relatively adjustable high and low camming surfaces pitchedabruptly from the first mentioned surface and engageable with saidelement to effect movement thereof in opposite directions from saidintermediate position.

11. In a circuit commutating device, the combination with a switchprovided with an oscillatable actuating element biased in one direction,said switch being movable to open and closed positions selectively byreverse movements of said element to extreme positions and said elementbeing returnable to a given intermediate position after opening orclosing said switch without effecting further circuit change by thelatter, of an oscillatable cam engaged by said element under its bias,said cam comprising relatively adjustable parts providing high and lowcamming surfaces to be adjusted relatively and an intermediate activesurface which is coextensive with the space between the'high' and lowcamming surfaces for different adjustments of the latter and which isconcentric to the axis of said cam and of a radius y to cause saidelement to assume said intermediate position.

JOHN L. DEFANDORF. HOWARD E. HODGSON.

